Deriscope

The Excel Derivatives Periscope

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Vol_Spec__Vol_Type__Normal

Variation of the Vol Spec::Vol Type::Black whereby dF = σdw that results in F(T) being normally distributed.
E{ max(F(T)-K,0) } can be then calculated through a formula known as Bachelier formula.
Note that the normal vol determines the absolute size of the fluctuation around the starting value, in contrast to the Black vol that measures the relative deflection.